High-power laser systems are being developed for a number of military and commercial applications. Some high-power laser systems use planar waveguide (PWG) amplifiers to amplify lower-power input signals and generate higher-power output signals. A conventional PWG amplifier includes a core region that receives a lower-power input signal and generates a higher-power output signal, and the core region is typically surrounded by cladding layers having a different refractive index than the core region. Pump energy received by the PWG amplifier provides the energy needed by the core region for optical amplification of the input signal.
Unfortunately, conventional PWG amplifiers can have very complex opto-mechanical and thermo-optic designs. For example, some conventional yttrium aluminum garnet (YAG) PWG amplifiers require complex coating configurations with various coating types on different surfaces of the amplifiers, complex multilayer cooling interfaces, and complex management of spilled pump light. Moreover, conventional YAG PWG amplifiers are often mechanically fragile devices that can be damaged relatively easily.
For these and other reasons, it can be costly, time consuming, and difficult to manufacture conventional PWG amplifiers. Also, defects can often arise in the manufacturing process. For instance, heat sinks are often pressed onto various surfaces of PWG amplifiers at high pressures, which can cause deformation of the heat sinks, the core region, or the cladding layers. Moreover, it can be difficult to avoid creating defects at the edges of the core region or the cladding layer. Further, the coupling of thermal energy into solid heat sinks can be inefficient, which results in inefficient cooling of the core region. In addition, it can be difficult or impossible to design a conventional PWG amplifier to compensate for thermal lensing or other non-uniform thermo-optic aberrations created in the core region during operation of the PWG amplifier.